UniversalMachExcServer: eliminate multiple implementation inheritance

util/mach/exc_server_variants.h

 // Copyright 2014 The Crashpad Authors. All rights reserved.
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.
 // You may obtain a copy of the License at
 //
 //     http://www.apache.org/licenses/LICENSE-2.0
 //
 // Unless required by applicable law or agreed to in writing, software
 // distributed under the License is distributed on an "AS IS" BASIS,
@@ skipping 311 matching lines @@
                                 public MachExcServer::Interface {
  public:
   //! \brief An interface that the different request messages that are a part of
   //!     the `mach_exc` Mach subsystem can be dispatched to.
   class Interface {
    public:
     //! \brief Handles exceptions raised by `mach_exception_raise()`,
     //!     `mach_exception_raise_state()`, and
     //!     `mach_exception_raise_state_identity()`.
     //!
-    //! When used with UniversalMachExcServer, this also handles exceptions
-    //! raised by `exception_raise()`, `exception_raise_state()`, and
-    //! `exception_raise_state_identity()`.
-    //!
     //! For convenience in implementation, these different “behaviors” of
     //! exception messages are all mapped to a single interface method. The
     //! exception’s original “behavior” is specified in the \a behavior
     //! parameter. Only parameters that were supplied in the request message
     //! are populated, other parameters are set to reasonable default values.
     //!
     //! The meanings of most parameters are identical to that of
     //! MachExcServer::Interface::CatchMachExceptionRaiseStateIdentity().
     //!
     //! \param[in] behavior `MACH_EXCEPTION_CODES | EXCEPTION_DEFAULT`,
     //!     `MACH_EXCEPTION_CODES | EXCEPTION_STATE`, or
     //!     `MACH_EXCEPTION_CODES | EXCEPTION_STATE_IDENTITY`, identifying which
     //!     exception request message was processed and thus which other
-    //!     parameters are valid. When used with UniversalMachExcServer, \a
-    //!     behavior can also be `EXCEPTION_DEFAULT`, `EXCEPTION_STATE`, or
-    //!     `EXCEPTION_STATE_IDENTITY`.
+    //!     parameters are valid.
     virtual kern_return_t CatchMachException(
         exception_behavior_t behavior,
         exception_handler_t exception_port,
         thread_t thread,
         task_t task,
         exception_type_t exception,
         const mach_exception_data_type_t* code,
         mach_msg_type_number_t code_count,
         thread_state_flavor_t* flavor,
         const natural_t* old_state,
@@ skipping 67 matching lines @@
 //! field, from `exception_data_type_t` to `mach_exception_data_type_t`.
 //! This is achieved by implementing SimplifiedExcServer::Interface and having
 //! it forward translated messages to SimplifiedMachExcServer::Interface, which
 //! is left unimplemented here so that users of this class can provide their own
 //! implementations.
 class UniversalMachExcServer
     : public MachMessageServer::Interface,
       public internal::SimplifiedExcServer::Interface,
       public internal::SimplifiedMachExcServer::Interface {
  public:
+  //! \brief An interface that the different request messages that are a part of
+  //!     the `exc` and `mach_exc` Mach subsystems can be dispatched to.
+  class Interface {
+   public:
+    //! \brief Handles exceptions raised by `exception_raise()`,
+    //!     `exception_raise_state()`, `exception_raise_state_identity()`,
+    //!     `mach_exception_raise()`, `mach_exception_raise_state()`, and
+    //!     `mach_exception_raise_state_identity()`.
+    //!
+    //! For convenience in implementation, these different “behaviors” of
+    //! exception messages are all mapped to a single interface method. The
+    //! exception’s original “behavior” is specified in the \a behavior
+    //! parameter. Only parameters that were supplied in the request message
+    //! are populated, other parameters are set to reasonable default values.
+    //!
+    //! The meanings of most parameters are identical to that of
+    //! MachExcServer::Interface::CatchMachExceptionRaiseStateIdentity().
+    //!
+    //! \param[in] behavior `EXCEPTION_DEFAULT`, `EXCEPTION_STATE`,
+    //!     or `EXCEPTION_STATE_IDENTITY`, possibly with `MACH_EXCEPTION_CODES`
+    //!     ORed in. This identifies which exception request message was
+    //!     processed and thus which other parameters are valid.
+    virtual kern_return_t CatchMachException(
+        exception_behavior_t behavior,
+        exception_handler_t exception_port,
+        thread_t thread,
+        task_t task,
+        exception_type_t exception,
+        const mach_exception_data_type_t* code,
+        mach_msg_type_number_t code_count,
+        thread_state_flavor_t* flavor,
+        const natural_t* old_state,
+        mach_msg_type_number_t old_state_count,
+        thread_state_t new_state,
+        mach_msg_type_number_t* new_state_count,
+        const mach_msg_trailer_t* trailer,
+        bool* destroy_complex_request) = 0;
+
+   protected:
+    ~Interface() {}
+  };
+
   //! \brief Constructs an object of this class.
-  UniversalMachExcServer();
+  //!
+  //! \param[in] interface The interface to dispatch requests to. Weak.
+  explicit UniversalMachExcServer(Interface* interface);
 
   // MachMessageServer::Interface:
 
   bool MachMessageServerFunction(const mach_msg_header_t* in_header,
                                  mach_msg_header_t* out_header,
                                  bool* destroy_complex_request) override;
 
   mach_msg_size_t MachMessageServerRequestSize() override;
   mach_msg_size_t MachMessageServerReplySize() override;
 
   // internal::SimplifiedExcServer::Interface:
 
   kern_return_t CatchException(exception_behavior_t behavior,
                                exception_handler_t exception_port,
                                thread_t thread,
                                task_t task,
                                exception_type_t exception,
                                const exception_data_type_t* code,
                                mach_msg_type_number_t code_count,
                                thread_state_flavor_t* flavor,
                                const natural_t* old_state,
                                mach_msg_type_number_t old_state_count,
                                thread_state_t new_state,
                                mach_msg_type_number_t* new_state_count,
                                const mach_msg_trailer_t* trailer,
                                bool* destroy_complex_request) override;
 
+  // internal::SimplifiedMachExcServer::Interface:
+
+  kern_return_t CatchMachException(exception_behavior_t behavior,
+                                   exception_handler_t exception_port,
+                                   thread_t thread,
+                                   task_t task,
+                                   exception_type_t exception,
+                                   const mach_exception_data_type_t* code,
+                                   mach_msg_type_number_t code_count,
+                                   thread_state_flavor_t* flavor,
+                                   const natural_t* old_state,
+                                   mach_msg_type_number_t old_state_count,
+                                   thread_state_t new_state,
+                                   mach_msg_type_number_t* new_state_count,
+                                   const mach_msg_trailer_t* trailer,
+                                   bool* destroy_complex_request) override;
+
  private:
   internal::SimplifiedExcServer exc_server_;
   internal::SimplifiedMachExcServer mach_exc_server_;
+  Interface* interface_;  // weak
 
   DISALLOW_COPY_AND_ASSIGN(UniversalMachExcServer);
 };
 
 //! \brief Recovers the original exception, first exception code, and signal
 //!     from the encoded form of the first exception code delivered with
 //!     `EXC_CRASH` exceptions.
 //!
 //! `EXC_CRASH` exceptions are generated when the kernel has committed to
 //! terminating a process as a result of a core-generating POSIX signal and, for
@@ skipping 71 matching lines @@
 //!     \a behavior is not a state-carrying behavior, or when it is a
 //!     state-carrying behavior and \a set_thread_state is `true`.
 //!     `MACH_RCV_PORT_DIED` is used when \a behavior is a state-carrying
 //!     behavior and \a set_thread_state is `false`.
 kern_return_t ExcServerSuccessfulReturnValue(exception_behavior_t behavior,
                                              bool set_thread_state);
 
 }  // namespace crashpad
 
 #endif  // CRASHPAD_UTIL_MACH_EXC_SERVER_VARIANTS_H_